The National Children's Study Vanguard Phase supported a formative research program that included the development and assessment of tools, instruments, methods and assays to address the assessment of child health. The preliminary results of the formative research program examining health measurements produced an initial framework and validated multiple instruments that are relevant for assessing child health and well being at several relevant ages.The National Children's Study is mandated by Public Law 106-310 Section 1004 to plan, develop, and implement a prospective cohort study, from birth to adulthood, to evaluate the effects of both chronic and intermittent exposures on child health and human development and is required to incorporate behavioral, emotional, educational, and contextual consequences to enable a complete assessment ofthe physical, chemical, biological and psychosocial environmental influences on children 's well-being.